In modern circumstances, it is difficult and expensive to train soldiers and military defense personnel in the effective use of high-powered rapid-fire machine guns, by simply allowing such individuals to practice using the actual guns with live ammunition. The ammunition rounds are expensive, for example costing up to five dollars per round. The cost of ammunition alone quickly multiplies when it is recognized that a typical machine gun is capable of firing hundreds of rounds per minute. Adequate space for a practice gunnery range may not be readily available. Increased cost is involved in transporting the personnel and the equipment to suitable remote locations where adequate gunnery practice can be performed. Safety is always a major consideration when live ammunition rounds are fired, both to military personnel involved in gunnery practice and to non-military personnel who may be adjacent to the gunnery range. It is difficult to instruct during a live ammunition training session due to the noise and safety considerations involved when others are involved in similar, close-by, live-ammunition practice activities. Furthermore, it may be difficult to vary the targets quickly at a live-ammunition gunnery range.
These problems and practical constraints are exacerbated when training individuals to shoot from a moving vehicle such as a helicopter. If live ammunition practice is attempted from a moving helicopter, a large space is required in order to maneuver the helicopter and to provide targets and adequate safety barriers, especially when multiple individuals are involved in similar simultaneous training exercises. As a result, live gun practice requires considerable space, and the cost of operating the helicopter greatly multiplies the overall training cost.
Because of these and other considerations, simulated weapon training programs have been developed for teaching purposes. Such training programs use imitation machine guns which closely simulate the sensational aspects and the mechanical and physical requirements of firing actual machine guns. Firing is simulated by reproducing effects which mirror the sensual perceptions associated with firing the actual machine gun. The environment and the targets are electronically displayed, allowing them to be more easily varied and to simulate movement of the targets and the machine gun. The trajectory of the simulated bullet fired is also calculated. In those cases where the simulated fired bullet emulates a tracer, the trajectory of that simulated bullet is also displayed in the surrounding environment.
For helicopter gun training, the imitation machine gun is mounted in an open door of an imitation portion of the helicopter fuselage. The environment and the targets are displayed outside of the open door. The portion of the imitation helicopter fuselage is moved or shaken in a manner similar to the movement of an actual helicopter in flight while the display of the surrounding environment and the targets are moved to simulate the flight path of the helicopter.
Simulated weapons training programs offer other benefits. Environments of remote areas of the world may be simulated, thereby providing training exposure to such environments prior to actually deploying the military personnel to those locales. The accuracy of the training program and the abilities of the individuals trained may be assessed. The accuracy in shooting, and the success of the training itself, is gauged by comparing the calculated, projected trajectory of the simulated bullets relative to the displayed targets. The number of simulated rounds fired may also be counted to evaluate the efficiency of the individual doing the shooting. Other factors can be evaluated from the vast amount of information available from such computer-based simulated weapons training programs.
Of course, to be effective for training purposes, it is necessary to create a realistic simulated environment and a realistic experience of firing the imitation machine gun. Such simulation is accomplished principally by multiple computer systems which are programmed to perform their specific simulation activities in coordination with each other. In the end, the capability of the simulated weapons training program to imitate the actual use of the actual machine gun in an actual environment is the ultimate measure of effective and successful training.
Individuals become accustomed to the imitation machine gun due to the amount of simulated training received. Because of the familiarity gained from training with the imitation machine gun, use of the imitation machine gun should be essentially the same as the use of the actual machine gun; otherwise, differences in functionality or performance create unexpected problems or difficulties when using the actual machine gun.
One of the important aspects of training with an imitation machine gun is to simulate the recoil of firing an actual machine gun. Recoil in an actual machine gun occurs in response to firing an ammunition round. A momentary rearward impact occurs in reaction to the forward acceleration of the bullet moving out of the barrel and in reaction to a reciprocating movement of an internal bolt of the gun. The explosive force from firing the round drives the bolt rearward against the force of a bolt actuating spring. The rearward movement of the bolt automatically ejects the spent casing, withdraws the next live round from the ammunition belt, expels a connection link which joined the withdrawn round to the next round of the ammunition belt, positions the withdrawn round on the bolt for loading and firing, and advances the ammunition belt to locate the next round to undergo similar actions after active round has been fired. Depressing the trigger enables the compressed bolt actuating spring to drive the bolt forward to load the round into a firing chamber and then fire that loaded round. The pressure from the exploded round drives the bolt rearwardly against the compression force of the bolt actuating spring. The sequence of events continues in the same manner with each subsequent pull of the trigger, or the sequence of events continues repetitively and continuously while the trigger remains depressed. Each ammunition round fired, accompanied by the reciprocating movement of the bolt in the manner described, creates a reactive impact. The individual operating the gun feels the sensation of this reaction as recoil of the machine gun. One very effective recoil simulation device, and its method of use, are described in the above-referenced US patent application.
To ready an actual machine gun for firing live ammunition rounds from a newly-loaded ammunition belt loaded, the operator must “charge” the bolt. Charging the bolt involves manually moving the bolt rearward against the force of the internal bolt actuating spring. Charging the bolt removes the first round from the ammunition belt and positions the removed round on the bolt for loading and firing. Charging the bolt enables the compressed bolt actuating spring to drive the bolt forward to load and fire the round. Thereafter, the explosion from firing that round drives the bolt rearward and compresses the bolt actuating spring to enable the continuous repetition of these actions with each subsequent pull of the trigger or on a continuous basis while the trigger remains depressed.
Loading a simulated ammunition belt in an imitation machine gun is also an important part of training to use the actual machine gun. The imitation machine gun must emulate the functionality of charging the bolt each time a new simulated ammunition belt is loaded. After simulated ammunition belt is loaded and the bolt is charged, the recoil simulator mechanism of the imitation machine gun simulates the recoil impacts generated by firing rounds and the reciprocation of the bolt. When the last round of the simulated ammunition belt is fired stimulatively, the bolt is released from its charged position. The bolt in the imitation machine gun thereafter assumes the same position that the bolt of an actual machine gun assumes after the last round of an actual ammunition belt has been fired.
One previous technique used in an imitation machine gun to simulate the action of charging the bolt involves holding the bolt in the charged position after the bolt has been manually charged by the operator. A holding pawl of the imitation machine gun pivots into contact with the bolt in the charged position to restrain the bolt against the considerable compression force from the bolt actuating spring. A spring pivots the holding pawl into position to restrain the bolt when the bolt is charged. The holding pawl is intended to restrain the bolt while the recoil simulation device generates the impacts which simulate firing the rounds from the simulated ammunition belt loaded into the imitation machine gun. A solenoid acts against the holding pawl to pivot it and release the bolt when all of the rounds of the simulated ammunition belt have been fired stimulatively. The released bolt moves forward to the position of the bolt in an actual machine gun after the last round of an actual ammunition belt has been fired. Thereafter, in both the actual and the imitation machine guns, a new ammunition belt must be loaded and the bolt must be charged before firing can commence again.
Often, the frictional forces acting on the holding pawl from the bolt and the forces from the pawl holding spring are too much for the solenoid to overcome and release the bolt. A failure to release the bolt when all of the rounds of the simulated ammunition belt has been fired stimulatively prevents the user from executing all of the actions necessary to load another simulated ammunition belt and ready the imitation machine gun for firing. On the other hand, if the pawl holding spring is weakened enough to allow the solenoid to pivot the pawl and release the bolt, the pawl holding spring is typically not strong enough to maintain the holding pawl in the bolt restraining position under the influence of repetitive recoil impacts generated by the recoil simulation device. Under such circumstances, the bolt is released prematurely before all of the rounds of the simulated ammunition belt have been fired.
In both cases, where the bolt is not released after all of the rounds of the simulated ammunition belt have been fired stimulatively, or where the bolt is released prematurely before all the rounds of the simulated ammunition belt have been fired stimulatively, dissimilarities in the performance of the imitation machine gun compared to the actual machine gun occur. The operator of the imitation machine gun is required to perform different and unusual activities which are not involved in operating the actual machine gun. As a result, the quality of the training is compromised. Furthermore, the resulting erratic effects have the potential of adversely influencing the coordination of the computer systems which control the simulated weapons training program, because those computer systems anticipate firing the full number of simulated rounds of the simulated ammunition belt. As a result, the training experience may be disrupted.